Tubular combustion chamber lining for forced flow steam generators



Jan. 6, 1959 A. LIEBERHERR 2,867,416

TUBULAR coususuou CHAMBER LINING FOR FORCED FLOW STEAM GENERATORS FiledJune 30, 1954 WWW m in

v G J 6 Lfl a p 54 g 8! o a n m o v k a y :4 INVENTOR. \J I a IART'HuEL/EBEEHERR.

/ ATTORNEK nited Slitgs TUBULAR COMBUSTION CHAMBER LINING FOR FORCEDFLOW STEAM GENERATQRS Arthur Lieberherr, Winterthur, Switzerland,assignor to Sulzer Freres, Socit Anonyme, Winterthur, Switzerland, acorporation of Switzerland The present invention relates to a tubularcombustion chamber lining for forced flow steam generators, particularlyfor steam generators operated at the critical or at super-criticalpressure.

The lining according to the invention consists of adjacent paralleltubes whose ends are connected with tubular headersor collectors. Eachcollector receives the outlet ends of a group of tubes forming thecombustion chamber wall and the inlet ends of a group of tubes throughwhich the water or steam subsequently flows to another collector. Theaxially aligned headers or collectors form two parallel rows, thecollectors of one row being axially staggered with respect to theheaders of the other row, so that the groups of tubes through which thewater or steam flows in series follow a zig-zag pattern. The individualtubes connecting two headers may be bent like hairpins. Thehairpin'bends may be replaced by short individual and axially alignedheaders.

Tubular evaporating or superheating heating surfaces forming, forexample, the inner lining of the walls of the combustion chamber of asteam boiler, which heating surfaces are operated at subcriticalpressures must be so constructed that there is no separation of thesteam from the water and consequently no ununiform passage of operatingmedium through the individual parallel tube lines. In tube systems inwhich water is converted to steam at a pressure near or higher than thecritical pressure undesirable separation of water from steam can beavoided if the-lines of heating tubes extend continuously through thesteam generator without interruption by transverse connections orcollectors. Such long tube lines must be bent to follow a meander-likepattern and there-are spaces between the individual return bends whichare not covered by heating tubes and through which the flame or gasradiation may adversely affect and destroy the insulation or thebrickwork in the back of the tubes. A further disadvantage is theformation of ash and slag deposits in the spaces between the bends.Brickwork for the combustion chamber walls cannot be dispensed with ifthe tube lines are constructed as explained above.

If the combustion chamber walls are lined by individual tube groupsarranged in series, and if the ends of the tubes of each group areconnected with inlet and outlet headers, unheated downcomer tubes mustbe provided which entail additional expense and considerably increasethe weight of the plant without being useful as heating surfaces. Thedowncomer tubes which are useless for steam generation but which arecapable of storing a relatively great volume of high pressure and hightemperature operating medium constitute a considerable source of dangerin case of tube explosions.

The aforesaid disadvantages can be avoided in a simple manner byconstructing the combustion chamber walls or the interior lining thereofaccording to the invention.

The novel features which are considered characteristic of the inventionare set forth with particularity in the atent ice appended claims. Theinvention itself however and additional objects and advantages thereofwill best be understood from the following description of embodimentsthereof when read in conjunction with the accompanying drawing, in whichFig. 1 is a diagrammatic illustration of a combustion chamber wallformed of groups of parallel tubes, only a few tubes being shown;

Fig. 2 is a diagrammatic illustration of a modified combustion chamberwall formed of tubes bent like hairpins, the parallel rows of collectorswhich are interconnected by the tubes being in close vicinity;

Fig. 3 is diagrammatic illustration of 'a modification of the combustionchamber wall construction shown in Fig. 2, in which the hairpin bendsare replaced by short axially aligned headers;

Fig. 4 is a diagrammatic cross section through a combustion chamber wallaccording to Fig. 1;

Fig. 5 is a diagrammatic cross section through a combustion chamber wallaccording to Fig. 2;

Fig. 6 is a diagrammatic cross section through a combustion chamber wallaccording to Fig. 3.

The same numerals designate the same parts in all figures.

Referring more particularly to Fig. 1 of the drawing, numerals 1 and 2designate rows of axially aligned headers or collectors 3, 3' and 4, 4',4", respectively. Groups of parallel tubes 5, 5', and 5" are-connectedwith their ends to the'collec tors 3, 4; 4, 3'; 3', 4", respectively,collector 4 receiving the outlet ends of the pipe group 5 and the inletends of the following pipe group 5. The inlets and outlets of the tubesconnected to the collectors ofthe same row are all at substantially thesame elevation. The collectors forming the row 1 are placed in axiallystaggered relation to the collectors forming the row 2.

If the individual tubes are bent approximately in the middle of theirlength through 180 rectangularly to the plane of the drawing,arrangements are formed as shown in Figs. 2 and 3. In the modificationsshown in these figures, the collectors of the individual rows 1 and 2are formed by continuous tubes which are subdivided by transverse walls6 to produce individual collector sections in the row 1 and bytransverse walls 7 to produce individual collector sections in the row2. The collector rows 1 and 2 are in close proximity of each other.

In the embodiment according to Fig. 2 the heating tubes 8, 8', 8 arebent like hairpins, one end of each tube being connected with acollector section of row 1 and the other end of each-tube beingconnected with a collector section of row 2, the sequence of the tubesand headers being the same as in Fig. l.

1n the embodiment shown in Fig. 3 the hairpin bends are replaced byrelatively short collectors 10, 10', 10", there being an individualcollector for each pipe group 9, 9, 9", respectively. Instead ofindividual headers or collectors 10, 10', 10", a continuous pipe,subdivided by transverse interior walls, may be provided in the samemanner as the collectors forming the rows 1 and 2 in Fig. 2 areconstructed. The tube ends connected with the intermediate collectors 10preferably extend radially from the collectors and are connected withthe collectors along diametrically opposed lines.

The collectors are preferably so placed that they are not directlyexposed to the heat produced in the combustion chamber. They are eitherembedded in the brickwork (top of Fig. 4) or arranged outside of thebrickwork or heat insulation (bottom of Fig. 4).

The hairpin bends of .the modification shown in Fig. 2 are also embeddedin the brickwork or insulation (Fig. 5), or arranged outside thereof.The same is done with the 7 top.

The combustion chamber wall construction according I to the inventionensures reliable cooling of the walls and prevents blowing up andbursting of the tubes. Since in the arrangements according to Figs. 2and 3 the tubes connected with different collectors are spaced, weldingof the tube ends to the collectors is facilitated. It is also possibleto space the tube ends in the arrangement according to Fig.1 tofacilitate welding. A further advantage of the constructionis thatindividual tube units can easily be interchanged and relatively fewreplacement parts need be kept in stock. Brickwork can be reduced andeven omitted with a combustion chamber wall according to the invention,since the walls are formed completely by the adjacent tubes. Cost isfurther, reduced because no downcomer tubes are needed.

The invention is not limited to the illustrated embodiments. Thecollectors need not be arranged in staggered relation. The number oftubes in the individual groups depends on the capacity of the steamgenerator, on the tube diameters, and on the desired flow velocity ofthe water and/ or steam. The combustion chamber wall constructionaccording to the invention is of advantage also in steam generatorswhich are operated at a pressure I.

lower than, but close to the critical pressure of water.

What is claimed is: 1. In a tubular lining for a combustion chamber wallof a forced flow steam generator, a plurality of parallel tubes, eachtube having an inlet end and an outlet end,. a first and a secondsubstantially parallel row 'of axially aligned substantially tubularheaders placed at a right angle to said tubes at one end thereof, a rowof axially aligned intermediate substantially tubular collectors placedat a right angle to said tubes at the other end thereof, the inlet endsof a first group of said tubes being connected with a first of saidheaders of said first row,

the outlet ends of the tubes of said first group being,

connected with a first of said intermediate collectors, the inlet endsof the tubes of a second group being connected with said firstintermediate collector, the outlet ends of the tubes of said secondgroup being connected with a first of said headers of said second row, athird group of said tubes having their inlet ends connected with saidfirst header of said second row, the outlet ends of the tubes of saidthird group being connected with a second of said intermediatecollectors, a fourth group of tubes having their inlet ends connectedwith said second intermediate collector and having their outlet endsconnected with a second of said headers of the first row. the inlet endsof a fifth group of said tubes being connected with said second headerof said first row, the outlet ends of said tubes of said fifth groupbeing connected with a third of said intermediate collectors, the inletends of a sixth group of said tubes being connected with said thirdintermediate collector, and the outlet ends of the tubes of said sixthgroup being connected with a second header ofsaid second row of headers.

2. A tubular lining as defined in claim 1 in which said tube ends whichare connected with said intermediate collectors extend substantiallyradially of the respective header, the outlet ends of the tubes of onegroup and the inlet ends of the tubes of the other group of tubesconnected to the same intermediate collector.being connected with saidintermediate collector along substantially diametrically opposed lines.

3. In a tubular lining for a combustion chamber wall of a forced flowsteam generator, a first row of axially aligned substantially tubularheaders, a second row of axially aligned substantially tubular headers,a first group of parallel tubes having inlet ends connected with aheader of the first row and having outlet ends connected with a headerof the second row, a second group of parallel tubes having inlet endsconnected with said header of the second row and having outlet endsconnected with a consecutive header of the first row, and intermediatecollectors individuallyinterposed in said groups of tubes.

4. In a tubular combustion chamber wall lining according to claim 3 andwherein said first row of headers ,is-adjacent to and parallel to saidsecond row of headers and at one end of the wall lined by said tubes,said collectors being arranged in said tubes substantially halfwaybetween the inlet ends and the outlet ends of said tubes and at theother end of the wall lined by said tubes.

5. In a tubular combustion chamber wall lining according to claim 4 andwherein the tubes of a group which tubes extend between a header of thefirst row and the collector interposed in said group are interspersedbetween the tubes of the same group which tubes extend between saidcollector and a header of the second row.

6. In a tubular combustion chamber Wall lining according to claim 4 andwherein said tubes terminate in said collectors and extend from saidcollectors at substantially diametrically opposed locations.

References Cited in the file of this patent UNITED STATES PATENTS320,647 Gannon June 23, 1885 1,959,866 Jacobus May 22, 1934 1,975,503Engler Oct. 2, 1934 FOREIGN PATENTS 828,331 Germany Jan. 7, 1952 613,659Germany May 23, 1935

